All but the top three post links of the Relevant Posts section seem fine for me. That makes absolutely no sense, since they’re all using the same link function though. It implies that somehow, $bb_post = bb_get_post( get_post_id( $post_id ) ); (line 1638, functions.bb-template.php) isn’t being set properly for those… so yes, I’m guessing it’s either a bug or something’s wrong with some posts in your database. Could you confirm whether that’s consistently happening on other posts in searches too?